To assure quality, circuit boards produced for commercial consumption are often subject to vigorous testing. One scheme for circuit board testing requires the placing of a circuit board on a circuit tester. The circuit tester has a connection surface consisting of an array of pin-shaped connectors called a "bed of nails". The pin-shaped connectors are placed on springs so that a template may be placed on top of the array of pin-shaped connectors depressing some of the connectors and allowing only selected connectors to pass through the the template. The circuit board may then be placed on the bed of nails so that the pin-shaped connectors make electrical contact between the circuit board and the circuit tester at selected contact points on the circuit board where the pin-shaped connectors pass through the template. Once electrical connection is made, the circuit tester can couple electronic signals to the circuit board verifying that the circuit board functions correctly.
Occasionally, proper connection between the circuit board and the circuit tester is not established at all selected contact points. When this happens the circuit tester is unable to couple electronic signals properly to the circuit board, which may result in an incorrect determination that the circuit board is defective. In order to circumvent this difficulty, verification of electrical connection between the circuit board and circuit tester can be performed.
One method to verify electrical connection is to place a first electrical probe on a contact point on the circuit board and a second electrical probe on a connection pin which should be electrically coupled to the contact point. Once these probes are in place the impedence between the two probes can be measured to determine whether electrical contact has been established. This method, however, is time-consuming as an operator would first need to determine which contact points are supposed to be coupled to which connection pins. Furthermore, once an appropriate contact point and a corresponding connection pin are discovered, placing of the first and second probes on the selected contact point and connection needs to be done simultaneously in order to determine whether they are electrically coupled.